1. An underground network of passages, chambers, or other cavities. 2. The caves in a given area related to each other hydrologically, whether continuous or discontinuous from a single opening [10]. Synonyms: (French.) reseau souterrain; (German.) Hohlensystem; (Greek.) speleothes systema, thiction; (Italian.) sistema carsico sotterraneo; (Russian.) sistema podzemnih pescher; (Spanish.) sistema de cavidades; (Turkish.) magara sistemi, serisi; (Yugoslavian.) pecinski (spiljski) sistem, amski sistem. See also cave; cave group; cave series; cavern.